At least half of cross-border trade invoices are in dollars. That is five times America’s share of world goods imports, and three times its share of exports. The dollar is the preferred currency of central banks and capital markets, accounting for close to two-thirds of global securities issuance and foreign-exchange reserves. The world’s financial rhythm is American: when interest rates move or risk appetite on Wall Street shifts, global markets respond. The world’s financial plumbing has Uncle Sam’s imprint on it, too. Most international transactions are ultimately cleared in dollars through New York by American “correspondent” banks.